1. Field of the Invention
This invention relates in general to air bearing sliders used in magnetic recording disk drives, and more particularly to a process for using polymer brush formation in single slider fabrication.
2. Description of the Background Art
Disk drives using magnetic recording of digital information store most of the information in contemporary computer systems. Disk drives have at least one rotating disk with discrete concentric tracks of data. There is at least one recording head typically having a separate write element and read element for writing and reading the data on the tracks. The recording head is constructed on a slider and the slider is attached to a suspension. The combination of the recording head, slider, and suspension is called a head gimbal assembly. In addition, there is an actuator which positions the recording head over the specific track of interest. The actuator first rotates to seek the track of interest and after positioning the recording head over that track maintains the recording head in close registration to that track. The disk in a disk drive has a substrate and a magnetic layer on the substrate for magnetic recording.
The slider carrying the recording head has a surface upon which an air bearing is constructed. The purpose of the air bearing is to allow the slider to float on a cushion of air and to be positioned close to the disk surface. The density of recorded data on the disk surface generally increases with each new disk drive product. As the density of recorded data increases there is an continuing need to improve the tolerance of the flying height of the finished slider over the surface of the disk and to improve the dimensional control of the recording transducers.
Recording heads are constructed on a wafer using thin film methods. After the construction of the recording heads, the wafer is sliced into rows. Each row will typically have 20 to 80 recording heads. The row is first lapped in order to give the final dimensions to the read and write elements. For very high recording density, row lapping does not deliver the required dimensional control of stripe height for the read element and throat height for the write element. After lapping, the air bearings are then simultaneously constructed on one surface of the row. First, a relatively thick layer of photoresist is deposited on the surface by either spin coating or applying a sheet of photoresist. The relatively thick layer of photoresist obtained by spin coating or by applying a sheet limits the feature size which can be created on the air bearing. Alternatively, a polymer coating may be applied to the row by absorbing polymers onto the surface. This absorption procedure with pre-formed polymer molecules generally results in coatings which are too thin to resist the subsequent milling or etching. The deposition of the coating is followed by pattern creation and milling or etching.
If the rows are first sliced into individual sliders and then the construction of the air bearing and the lapping is performed on each single slider, the precision of the air bearing features and the dimensional control of the recording heads can be significantly improved. However, the methods used to construct air bearings on unsliced rows are not as appropriate for use on a single slider. For example, spin coating photoresist onto a single slider is very difficult to control. Once the rows are sliced into individual sliders and placed on carriers, the methods used for lithography must be suitable for use on single sliders.
From the foregoing it will be apparent that there is a need for a method of constructing an air bearing which is suitable for use on a single slider.